2018 Euro tour posters

How quickly have the posters been selling out this tour? I'm hoping to catch one or two shows later this tour and am trying to figure out how early I need to arrive (or whether I need to carve out time to visit the merch store during the day) to safely get a poster.

I’m not a big poster guy - I have several, don’t get me wrong. But for as long as I can remember, there have been plenty of posters for sale inside the venue (and you can actually do something with your day other than waiting in the outside merch line).